This invention relates to ultrasonic diagnostic imaging systems and, in particular, to ultrasonic diagnostic imaging systems which produce images that are stabilized in the presence of probe or anatomical motion.
Ultrasonic diagnostic imaging systems enable the diagnosis of the anatomy of a patient by real time two and three dimensional imaging. The quality and resolution of ultrasonic images has become advanced to the point where physicians can locate and study even the smallest anatomical details, such as heart valve motion and flow characteristics in individual blood vessels. But motional effects can render such advances ineffective. For instance, a physician may be trying to image the kidney of an infant to assess the bloodflow perfusion in the organ. The infant, however, will not comprehend this procedure and may struggle and squirm as the physician attempts to hold the ultrasound system probe in steady contact with the infant""s abdomen. The struggling of the infant can prevent any continuous steady probe contact, causing the anatomy in the image to jitter and move erratically as the probe moves involuntarily. The physician can attempt to overcome these circumstances by pressing the Freeze button to capture an image when she feels she has an adequate image of the kidney, but this can be a haphazard, hit-or-miss exercise. Under these conditions the physician may not be able to obtain images which enable a confident diagnosis.
Another example of deleterious motional effects even with a cooperative patient is cardiac imaging. A cardiologist may be imaging the heart and attempting to discern whether there are any jets or leaks from a heart valve. These effects can be very tiny in the image and may only appear momentarily when they are in the image plane or volume. However, as the heart beats it often does not do so in the same location, but can swing from side to side in the chest cavity. This movement of the entire organ can make focusing on a constant spot in the vicinity of a heart valve difficult. If the ultrasound system is being operated in the xe2x80x9czoomxe2x80x9d mode in which an enlarged portion of a larger field of view is being observed, the anatomy of interest can move completely out of the zoom field of view due to this motion. Again, motion can prevent the acquisition of images needed for a confident diagnosis. In this case the motion is of anatomy in the body rather than the ultrasound probe. It would be desirable for the ultrasound system to ameliorate these motional problems automatically to better facilitate the acquisition of diagnostically valid images under difficult imaging circumstances.